The effect of the antioxidant activity of plant extracts on the properties of gold nanoparticles

Synthesis of gold nanoparticles (phyto-AuNPs) with the use of leaf extracts (phytosynthesis) is based on the concept of Green Chemistry. The present study is conducted to discuss how antioxidant activity (AOA) of extracts from plant leaves impacts on the kinetics of phytosynthesis, the size of the formed nanoparticles, and the stability of their nanosuspensions. Results show that the formation rate of phyto-AuNPs suspensions accelerate due to the increase in the AOA of the extracts. Accompanying the use of transmission electron microscopy (TEM), UV-Vis-spectrophotometry and dynamic light scattering (DLS), it also has been found that higher AOA of the extracts leads to a decrease in the size of phyto-AuNPs, an increase in the fraction of small (d ≤ 5 nm), and a decrease in the fraction of large (d ≥ 31–50 nm) phyto-AuNPs, as well as an increase in the zeta potential in absolute value. Phyto-AuNPs suspensions synthesized with the use of extracts are more resistant to destabilizing electrolytes and ultrasound, as compared to suspensions synthesized using sodium citrate. Thus, the AOA of the extract is an important parameter for controlling phytosynthesis and predicting the properties of phyto-AuNPs. The proposed approach can be applied to the targeted selection of plant extract that will be used for synthesizing nanoparticles with desired properties. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Russian Foundation for Basic Research, RFBR: 17-03-00679_АFunding: This research was funded by the Russian Foundation for Basic Research, grant number 17-03-00679_А

Antioxidant Activity of Plants as an Indicator of the Environmental State

В статье рассматриваются природные и антропогенные факторы, влияющие на содержание антиоксидантов в растениях. Показана корреляция между содержанием антиоксидантов в растениях и состоянием окружающей среды. Проведена оценка антиоксидантной активности местных уральских растений, растущих в разных экологических условиях.The article examines natural and anthropogenic factors affecting the content of antioxidants in plants. A correlation has been shown between the content of antioxidants in plants and the state of the environment. An assessment of the antioxidant activity of local Ural plants growing in different environmental conditions has been carried out

Eco-Friendly Materials for Electrochemical Sensors

В статье рассматривается применение принципов «зеленой химии» в электрохимической сенсорике. Обсуждаются экологически чистые методы получения модифицирующих материалов для электрохимических сенсоров.The article discusses the application of "green chemistry" principles in electrochemical sensors. Environmentally friendly methods for obtaining modifying materials for electrochemical sensors are discussed

VOLTAMPEROMETRIC DETERMINATION OF NITRITE IONS IN NATURAL WATERS

The article discusses the main sources of environmental pollution with nitrite ions. The need for monitoring the nitrite content in environmental objects is shown, since nitrite ions are toxic substances that can harm human health. The development of an electrochemical sensor for the fast and accurate determination of nitrite ions in natural waters is discussed.В статье рассматриваются основные источники загрязнения окружающей среды нитрит-ионами. Показана необходимость контроля за содержанием нитритов в объектах окружающей среды, так как нитрит-ионы относятся к токсичным веществам, способным нанести вред здоровью человека. Обсуждается разработка электрохимического сенсора для быстрого и точного определения нитрит-ионов в природных водах

Carbon Paper Modified with Functionalized Poly(diallyldimethylammonium chloride) Graphene and Gold Phytonanoparticles as a Promising Sensing Material: Characterization and Electroanalysis of Ponceau 4R in Food Samples

This paper presents a novel eco-friendly sensing material based on carbon paper (CP) volumetrically modified with a composite nanomodifier that includes functionalized poly(diallyldimethylammonium chloride) graphene (PDDA-G) and phytosynthesized gold nanoparticles (phyto-AuNPs). The functionalization of graphene was justified by Fourier-transform infrared spectroscopy. The phyto-AuNPs (d = 6 nm) were prepared by “green” synthesis with the use of strawberry leaf extract. The sensing material was characterized using scanning electron microscopy, electrochemical impedance spectroscopy, and voltammetry. The research results indicated a more than double increase in the electroactive surface area; a decrease in the resistance of electron transfer on nanocomposite-modified CP, compared to bare CP. The phyto-AuNPs/PDDA-G/CP was used for the electrosensing of the synthetic dye Ponceau 4R. The oxidation signal of colorant enhanced 4-fold on phyto-AuNPs/PDDA-G/CP in comparison to CP. The effect of the quantity of nanomodifier, solution pH, potential scan rate, accumulation parameters, and differential pulse parameters on the peak current of Ponceau 4R was studied. Under optimal conditions, excellent sensory characteristics were established: LOD 0.6 nM and LR 0.001–2 μM for Ponceau 4R. High selectivity and sensitivity enable the use of the sensor for analyzing the content of Ponceau 4R in food products (soft drinks, candies, and popsicles) without additional sample preparation. © 2022 by the authors

Food Colorings: Benefit and Harms

В статье рассматриваются сферы применения натуральных и синтетических красителей. Обсуждается отрицательное влияние красителей и продуктов их распада на экосистему и здоровье человека. Обсуждаются существующие аналитические методы обнаружения красителей.The article discusses the scope of natural and synthetic dyes. The negative impact of dyes and their decay products on the ecosystem and human health is discussed. The existing analytical methods for the detection of dyes are discussed